How can I improve this PHP code?

Question

I have the php code below which help me get a photo's thumbnail image path in a script

It will take a supplied value like this from a mysql DB '2/34/12/thepicture.jpg' It will then turn it into this '2/34/12/thepicture_thumb1.jpg'

I am sure there is a better performance way of doing this and I am open to any help please

Also on a page with 50 user's this would run 50 times to get 50 different photos

// the photo has it is pulled from the DB, it has the folders and filename as 1
$photo_url = '2/34/12/thepicture_thumb1.jpg';
//build the full photo filepath
$file = $site_path. 'images/userphoto/' . $photo_url;
// make sure file name is not empty and the file exist 
if ($photo_url != '' && file_exists($file)) {
    //get file info
    $fil_ext1 = pathinfo($file);
    $fil_ext = $fil_ext1['extension'];
    $fil_explode = '.' . $fil_ext;
    $arr = explode($fil_explode, $photo_url);
    // add "_thumb" or else "_thumb1" inbetween 
    // the file name and the file extension 2/45/12/photo.jpg becomes 2/45/12/photo_thumb1.jpg
    $pic1 = $arr[0] . "_thumb" . $fil_explode;
    //make sure the thumbnail image exist
    if (file_exists("images/userphoto/" . $pic1)) {
     //retunr the thumbnail image url
     $img_name = $pic1;
    }
}

1 thing I am curious about is how it uses pathinfo() to get the files extension, since the extension will always be 3 digits, would other methods of getting this value better performance?

Answer 1

$img_name = preg_replace('/^(.*)(\..*?)$/', '\1_thumb\2', $file);

Edit: bbcode disappeared with \.

Answer 2

Why are you even concerned about the performance of this function? Assuming you call it only once (say, when the "main" filename is generated) and store the result, its runtime should be essentially zero compared to DB and filesystem access. If you're calling it on every access to re-compute the thumbnail path, well, that's wasteful but it's still not going to be significantly impacting your runtime.

Now, if you want it to look nicer and be more maintainable, that's a worthwhile goal.

Answer 3

Is there a performance problem with this code, or are you just optimizing prematurely? Unless the performance is bad enough to be a usability issue and the profiler tells you that this code is to blame, there are much more pressing issues with this code.

To answer the question: "How can I improve this PHP code?" Add whitespace.

Answer 4

The best optimization for this code is to increase it's readability:

// make sure file name is not empty and the file exist 
if ( $photo_url != '' && file_exists($file) ) {

    // Get information about the file path
    $path_info = pathinfo($file);

    // determine the thumbnail name 
    // add "_thumb" or else "_thumb1" inbetween 
    // the file name and the file extension 2/45/12/photo.jpg
    // becomes 2/45/12/photo_thumb.jpg
    $pic1 = "{$path_info['dirname']}/{$path_info['basename']}_thumb.{$fil_ext}";

    // if this calculated thumbnail file exists, use it in place of
    // the image name
    if ( file_exists( "images/userphoto/" . $pic1 ) ) {
        $img_name = $pic1;
    }
}

I have broken up the components of the function using line breaks, and used the information returned from pathinfo() to simplify the process of determining the thumbnail name.

Updated to incorporate feedback from @DisgruntledGoat

Answer 5

Performance-wise, if you're calling built-in PHP functions the performance is excellent because you're running compiled code behind the scenes.

Of course, calling all these functions when you don't need to isn't a good idea. In your case, the pathinfo function returns the various paths you need. You call the explode function on the original name when you can build the file name like this (note, the 'filename' is only available since PHP 5.2):

$fInfo = pathinfo($file);
$thumb_name = $fInfo['dirname'] . '/' . $fInfo['filename'] . '_thumb' . $fInfo['extension'];

If you don't have PHP 5.2, then the simplest way is to ignore that function and use strrpos and substr:

// gets the position of the last dot
$lastDot = strrpos($file, '.');
// first bit gets everything before the dot,
// second gets everything from the dot onwards
$thumbName = substr($file, 0, $lastDot) . '_thumb1' . substr($file, $lastDot);

Answer 6

The easiest way to fix this is to thumbnail all user profile pics before hand and keep it around so you don't keep resizing.